Since the hydrogen-production process is not yet fully efficient, this paper proposes a poly-generation system that is driven by a geothermal energy source and utilizes a combined Kalina/organic Rankine cycle coupled with an electrolyzer unit to produce, simultaneously, power and green hydrogen in an efficient way. A comprehensive thermodynamic analysis and an exergetic evaluation are carried out to assess the effect of key system parameters (geothermal temperature, high pressure, ammonia–water concentration ratio, and terminal thermal difference) on the performance of concurrent production of power and green hydrogen. Thereby, two configurations are investigated with/without the separation of turbines. The optimal ammonia mass fraction of the basic solution in KC is identified, which leads to an overall optimal system performance in terms of exergy efficiency and green hydrogen production rate. In both configurations, the optimal evaluation is made possible by conducting a genetic algorithm optimization. The simulation results without/with the separation of turbines demonstrate the potential of the suggested cycle combination and emphasize its effectiveness and efficiency. Exemplary, for the case without the separation of turbines, it turns out that the combination of ammonia–water and MD2M provides the best performance with net power of 1470 kW, energy efficiency of 0.1184, and exergy efficiency of 0.1258 while producing a significant green hydrogen amount of 620.17 kg/day. Finally, an economic study allows to determine the total investment and payback time of $3,342,000 and 5.37 years, respectively. The levelized cost of hydrogen (LCOH) for the proposed system is estimated at 3.007 USD/kg H₂, aligning well with values reported in the literature.

Since the hydrogen production process is not yet fully efficient, this paper proposes a poly-generation system which is driven by a geothermal energy source and utilizes a combined Kalina/Organic Rankine cycle coupled with an electrolyzer unit to produce simultaneously power and green hydrogen in an efficient way. A comprehensive ther-modynamic analysis and an exergetic evaluation are carried out to assess the effect of system key parameters (geothermal temperature, high pressure, ammonia-water concen-tration ratio, and terminal thermal difference) on the performance of concurrent produc-tion of power and green hydrogen. Thereby, two configurations are investigated with/without separation of turbines. The optimal ammonia mass fraction of basic solution in KC is identified that leads to an overall optimal system performance in terms of ex-ergetic efficiency and green hydrogen production rate. In both configurations, the optimal evaluation is made possible by conducting a genetic algorithm optimization. The simula-tion results without/with separation of turbines demonstrate the potential of the suggested cycle combination and emphasize its effectiveness and efficiency. Exemplary, for the case without separation of turbines, it turns out that the combination of ammonia-water and MD2M provides the best performance with net power of 1470 kW, energy efficiency of 0.1181, exergy efficiency of 0.1258 while producing a significant green hydrogen amount of 3194.208 Kg/day.

The present contribution proposes a novel geothermal-driven quad-generation system based on a new combined cycle and capable of simultaneously producing electricity, cooling, green hydrogen, and oxygen as value-added products. The system includes a primary Combined Power and Absorption Refrigeration Cycle (KC-ARC) driven by an ammonia-water mixture and coupled to a proton exchange membrane (PEM) electrolyzer for hydrogen and oxygen co-production and a second Kalina cycle for additional waste heat recovery. Next, for such multi-generation systems, impacts of major operating conditions on the system performance have not yet been comprehensively investigated. Indeed, in addition to an exergy efficiency, thermo-economic performance analysis and optimization method commonly reported, an evaluation in terms of sustainability assessment and total costs of green hydrogen and oxygen production along with electricity and cooling generation is carried out at the first time. Key parameters are the temperature of the geothermal source, the high pressure, and the ammonia basic mass fraction of the ammonia-water mixture. The results show that the proposed system can achieve a net power output of 242.7 kW, a hydrogen production rate of 103.59 kg/day, an oxygen production rate of 821.92 kg/day, and a cooling capacity of 1989 kW. At a geothermal temperature of 140°C, the energy and exergy efficiencies reach 0.4352 and 0.4355, respectively. Furthermore, optimization results obtained at an optimal temperature of 179.2°C reveal significant performance improvements, including increases of 38.34% and 6.75% in net powers 1 and 2, respectively, 38.03% in hydrogen production rate, 38% in oxygen production rate, and 3.45% improvements in both energy and exergy efficiencies. Finally, the average production costs of hydrogen and oxygen are estimated at 4.95 $/kg and 0.6237 $, respectively, with an exergetic sustainability index of 0.8653, confirming the sustainable and efficient nature of the proposed system.